Search Publications
Large amplitude nonlinear waves in Venus magnetosheath
Zhang, T. L.; Gedalin, M.; Balikhin, M. +1 more
Large-amplitude variations of the magnetic field in the Venusian magnetosheath are observed when the distance between the bow shock and the magnetic pileup boundary is small, of the order of the ion convective gyroradius. It is proposed that these oscillations are nonlinear standing waves. A theoretical model is developed within one-dimensional tw…
VLBI Observation of Microquasar Cyg X-3 during an X-Ray State Transition from Soft to Hard in the 2007 May-June Flare
Kim, Jeong-Sook; Kim, Soon-Wook; Kurayama, Tomoharu +3 more
We present a radio observation of microquasar Cyg X-3 during an X-ray state transition from ultrasoft to hard state in the 2007 May-June flare using the VLBI Exploration of Radio Astrometry at 22 GHz. During the transition, a short-lived mini-flare of <~ 3 hr was detected prior to the major flare. In such a transition, a jet ejection is believe…
A Combined Astrometric and Spectroscopic Study of Metal-Poor Binaries
Sozzetti, A.; Santos, N. C.; Latham, D. W. +1 more
In this work we present a study of binary systems in a metal-poor sample of solar type stars. The stars analyzed were rejected from two planet search samples because they were found to be binaries. Using available radial velocity and Hipparcos astrometric data, we apply different methods to find, for every binary system, a possible range of soluti…
Ultraviolet Spectroscopic Analysis of Transient Mass Flow Outburst in U Cephei
Sahade, Jorge; Kondo, Yoji; Giménez, Alvaro +4 more
Spectra from the International Ultraviolet Explorer taken in 1989 September over one full orbital period of U Cephei (U Cep, HD 5796) are analyzed. The TLUSTY and SYNSPEC stellar atmospheric simulation programs are used to generate synthetic spectra to which U Cep continuum levels are normalized. Absorption lines attributed to the photosphere are …
Theoretical constraints on the cross-tail width of bursty bulk flows
Chen, C. X.
The characteristic cross-tail width of bursty bulk flows (BBFs) in earth's plasma sheet was investigated at two stages of its life, one at its onset, the other when it is fully developed. Equilibrium domains with gradient of magnetic field are constructed. Interchange instability analysis of such domains yields the most unstable mode with the half…
Retrieving atmospheric dust opacity on Mars by imaging spectroscopy at large angles
Douté, S.; Ceamanos, X.; Appéré, T.
We propose a new method to retrieve the optical depth of Martian aerosols (AOD) from OMEGA and CRISM hyperspectral imagery at a reference wavelength of 1 µm. Our method works even if the underlying surface is completely made of minerals, corresponding to a low contrast between surface and atmospheric dust, while being observed at a fixed geo…
Multi-resolution digital terrain models and their potential for Mars landing site assessments
Muller, Jan-Peter; Warner, Nicholas H.; Gupta, Sanjeev +2 more
One of the key issues for planetary, especially Mars surface exploration, is how to make an objective assessment of criteria for landing sites selection for future rovers, sample return missions and landers considering topographic variables such as slope, altitude and roughness as well as their physical scattering properties. For these purposes, s…
The International Ultraviolet Explorer: Origins and Legacy
Willis, Allan J.
he International Ultraviolet Explorer (IUE) satellite was launched on 26 January 1978, and operated as a Guest Observer space observatory for nearly 19 years. IUE was, without doubt, one of the most successful astronomical facilities ever developed. Used by thousands of astronomers worldwide, it yielded over 100,000 UV spectra (in the wavelength r…
Galactic orbits of Hipparcos stars: Classification of stars
Bajkova, A. T.; Gontcharov, G. A.
The Galactic orbits of 27 440 stars of all classes with accurate coordinates and parallaxes of more than 3 mas from the Hipparcos catalogue, proper motions from the Tycho-2 catalogue, and radial velocities from the Pulkovo Compilation of Radial Velocities (PCRV) are analyzed. The sample obtained is much more representative than the Geneva-Copenhag…
The Chandra Local Volume Survey: The X-Ray Point-source Population of NGC 404
Skillman, E. D.; Kong, A. K. H.; Weisz, D. R. +4 more
We present a comprehensive X-ray point-source catalog of NGC 404 obtained as part of the Chandra Local Volume Survey. A new 97 ks Chandra ACIS-S observation of NGC 404 was combined with archival observations for a total exposure of ~123 ks. Our survey yields 74 highly significant X-ray point sources and is sensitive to a limiting unabsorbed lumino…